School principals fear Hong Kong universities will take in more pupils who have studied international curriculums at the expense of those who take local public exams.
The University of Hong Kong reserves about 20 per cent of its first-year degree places for those taking non-local exams, while the Hong Kong University of Science and Technology has stuck to a figure of 15 to 20 per cent.
Students who study international curriculums do not go though the local Joint University Programmes Admissions System (Jupas) and are known as non-Jupas students.
"How many families can afford to send their children to international schools or give extra tutorial support for their children to take international examinations?" the chairman of the Grant Schools Council, George Tam Siu-ping, said.
He said that ultimately the government should provide more university places.
Tam, who is also the principal of Wah Yan College, said a sixth-former at his school was admitted to HKU's faculty of medicine this year on the strength of his GCSE A-level results.
HKU registrar Henry Wai Wing-kun said the university's percentage of first-year degree places reserved for non-Jupas applicants had been stable for five years "but it has gone up from a decade ago, when there were fewer international schools and students doing international curriculum".
Besides those in international schools, non-Jupas candidates include those who take associate degree programmes and students in local schools who have taken international exams such as the General Certificate of Secondary Education (GCSE) or International Baccalaureate (IB) curriculum offered at some direct subsidy scheme schools.
Almost a quarter of English Schools Foundation graduates this year went on to local universities.
Students are worried about their chances of getting into university under new admission requirements since the launch this year of the Hong Kong Diploma of Secondary Education exam.
"Parents find it more viable for their children to do the GCSE and come back via non-Jupas," said Ronnie Cheng, principal of the elite Diocesan Boys' School (DBS), echoing Tam's concern.
Kenneth Fung, a fifth-former at DBS, is studying to take GCSE A Level exams early next year, as are a number of other pupils in his class.
"It seems hard to get good grades in the diploma," he said.